1. Field of the Invention:
The present invention relates to a precision router guide, and more particularly, to a novel and improved method and apparatus for guiding a router in the formation of slots of different widths, such as in the construction of wooden shelving for edge-wise joining of the shelves thereto and therein.
2. Description of the Prior Art:
Carpentry work frequently requires the formation of the tongue and groove or dado joint which provides a strong joining means for perpendicular configurations. The Rabbit Joint used for corner applications may be considered as a one sided dado joint and is formed in a similar manner. Both of these joints are commonly formed with the dado head cutter in conjunction with a table saw or radial arm saw. While this means is effective, particularly for production applications, it lacks the portability, flexibility, safety and economy that is required by many carpenters. The introduction of the high speed router has made it possible to form the dado and rabbit joints without these restrictions provided that a convenient guiding means could be developed.
One device which characterizes the prior state of the art in this regard is disclosed in U.S. Pat. No. 3,967,665 which is referred to as an adjustable routing template. It should be noted however, that this particular prior art device will not:
(1) Provide a uniform in depth cut if the material to be routed is not flat, or is warped. PA1 (2) Provide an accurate router cut to trim the workpiece at any angle by means of a straight external edge. PA1 (3) Provide an accurate router cut to cut a notch along the edge of the workpiece to create a rabbit joint. PA1 (4) Provide a depth of router cut which may be determined without compensating for the router guide frame thickness. PA1 (5) Provide an automatic, consistent means of inherently maintaining the router guide frame members in constant parallel relationship. PA1 (6) Provide a means for positioning the router guide squarely or at some other angle with respect to the workpiece by means of a calibrated square or protractor. PA1 (7) Provide a means for guiding the router without utilizing a guide bushing. A guide bushing restricts the versatility of the router and is generally not installed unless specifically required. PA1 (8) Provide relatively unobstructed visual and manual access to the workpiece without any substantial interference from the adjustable router guide; PA1 (9) Provide a simple calibration procedure for gauging the frame member spacing and position relative to the desired cut location; and PA1 (10) Provide a tool that is accurate, compact, rugged and convenient to use.
Because of these deficiencies in the prior art, router guides for cutting dado and rabbit joints are not widely used and, in fact, are generally unavailable. This situation will only be rectified if the state of the art is advanced to such an extent that these deficiencies are overcome.